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AMMA-UK WP3 – Convection and dynamics. Doug Parker Institute for Atmospheric Science School of Earth and Environment University of Leeds 29 November 2004. WP3 Objectives.

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Amma uk wp3 convection and dynamics

AMMA-UK WP3 – Convection and dynamics

Doug Parker

Institute for Atmospheric Science

School of Earth and Environment

University of Leeds

29 November 2004


Wp3 objectives
WP3 Objectives

To explain the basic dynamics and transport properties of the WAM system, including the diurnal cycle of the boundary layer control on the monsoon, and the response to shallow and deep cumulus convection.


Moist convection in the south, dry convection in the north (the Sahara): a ‘natural laboratory’ for tropical continental convection.

African Easterly Jet (AEJ) 600 hPa

Monsoonwinds

Water vapour 17/6/97


Deep convection (the Sahara): a

Shallow cumulus

Mixed layer


1. The analysis of the African Easterly Jet is good (the Sahara): a

Sahara

ITCZ

ECMWF analyses (Adrian Tompkins; in Thorncroft et al, BAMS 2003):


2. The forecast has systematic error (the Sahara): a

Courtesy Tompkins, ECMWF.

700 hPa zonal winds, averaged over August 2003

Systematic error! We need to represent the physics better.


3. Significnt errors in ECMWF PBL fields compared to observations

Potential temperature

Equivalent potential temperature

(Aida Diongue; in

Thorncroft et al., BAMS 03)


There is cool humid air too far north surface fluxes advective fluxes column radiation

There is cool, humid air too far north. observationsSurface fluxes?Advective fluxes?Column radiation?




Surface temperature (1200 UTC) and boundary layer TKE in the afternoon (around 1500 UTC)

Chris Taylor, CEH Wallingford


Wam dynamics
WAM dynamics afternoon (around 1500 UTC)

  • By day, the boundary layer ‘maps’ onto soil moisture

  • By night, airflow responds to pressure gradients


Wp3 objectives convection soil moisture diurnal
WP3 Objectives afternoon (around 1500 UTC)Convection-soil moisture-diurnal

  • WP3.1 To develop validated model case studies of the diurnal cycle of convection in the continental WAM, and over anomalies of soil moisture (with WP1; using OWP1, OWP3 and OWP4 data).

  • WP3.2 To use case studies to quantify the response of the WAM dynamics to Mesoscale Convective Systems (MCSs) (using OWP1,3,4).



Wp3 objectives transport
WP3 Objectives: Transport circulations

  • WP3.3 To quantify the transport properties of dry and moist convective circulations, on the mesoscale and the continental scale, through model case studies and through use of chemical tracers that act as markers of source regions and of air mass ages (with WP4). Within this, to model mixing in the monsoon layer and its implication for the monsoon fluxes (using OWP1,3,4 data).


C. M. Taylor circulationset al, QJRMS, 2005


Wp3 objectives synoptic
WP3 Objectives: synoptic circulations

  • WP3.4 To develop synoptic cases studies of AEW structure both north and south of the AEJ, and explore the interaction of these AEWs with soil moisture patterns (with WP1; using OWP1,3,4 data).

  • WP3.5 To describe the evolution of the SAL on synoptic and diurnal timescales.


Flight patterns
Flight patterns circulations

  • Stacked N-S legs in association with MCSs

  • Early morning / late evening

  • Long straight legs in boundary layer


Summary of soundbites
Summary of ‘soundbites’ circulations

  • The analysis of the African Easterly Jet is good

  • The forecast has systematic error

  • Significnt errors in ECMWF PBL fields compared to observations

  • The monsoon flow is active at night and in the morning


  • A circulationsfrican Monsoon Multidisciplinary Analyses

  • Afrikanske Monsun: Multidisiplinære Analyser

  • Afrikaanse Moesson Multidisciplinaire Analyse

  • Analisi Multidisciplinare per il Monsone Africano

  • Afrikanischer Monsun: Multidisziplinäre Analysen

  • Analisis Multidiciplinar de los Monzones Africanos

  • Analyses Multidisciplinaires de la Mousson Africaine


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